Archival articles are generally defined as objects of historical, aesthetic or sentimental significance, such as papers and photographs. Several attempts have been made to protect archival articles from the deleterious effects of impurities in the environment.
For example, previous attempts have been made to protect archival articles by storing them in containers designed to protect the archival articles from the deleterious effects of both impurities outside of the container and from residual chemicals within the container material. Cardboard containers have been coated with an acid in order to protect the contents of the container from alkaline fumes emitted from the adhesive used in container construction or sealing. Other containers have an inner layer incorporating an organic amide and an inorganic metal nitrate which inhibits metal corrosion.
Additionally, packages have been designed for photographic film in which a container or wrapping is substantially free from sulfur, ammonia, and turpentine. Such a package may also have a black, opaque outer layer and an inner layer which is inert towards light-sensitive, photographic emulsions.
Boxboards are also known which include a first layer of paperboard consisting of non-buffered, substantially pure alpha-cellulose and alkaline size, a second layer of a paperboard comprising alpha-cellulose, an alkaline buffer and an alkaline size and, between the first and second layers, a layer of water-impermeable plastic. The alkaline components may neutralize the acidic impurities in the environment of the archival article. The inner layer of the boxboard may be nonbuffered in order to avoid damage to the contents stored within the containers made from the boxboard.
However, the previous methods have not been sufficient to protect archival articles from all of the impurities in the environment of the archival articles. A wide variety of compounds are known to damage archival articles. For example, airborne pollutants from the surrounding atmosphere and the various by-products of deteriorating archival articles may contact and damage an archival article. For example, oxides of nitrogen may combine with moisture to form pollutants, such as nitric acid, which may contact and damage artifacts, such as photographs. Sulfur compounds may cause silver images, e.g. in photographs, microfilm, and microfiche, to fade by converting the metallic silver in the photographic layers to silver sulfide. Acids can also contact and damage photographs by bleaching and fading the silver image and causing the paper and gelatin support to become brittle. Peroxides, in concentrations as low as one part in thirty million, may also cause image oxidation and fading.
Previous studies have also detected degradation products from the archival articles themselves which may further damage archival articles. The degradation products may be mobile and may be transferred from one article to another by surface or gas phase diffusion. Deterioration may also produce by-products such as organic acids, low molecular weight ketones, aldehydes and phenols.